At present, personal authentication using biometric techniques is one of the most promising and rapidly developing trends, and methods and means that use fingerprints rank highly among such biometric techniques. Existing electronic devices, for example, mobile devices, use capacitive sensors for fingerprint recognition, but the methods employing the sensors may not provide an adequate level of security. Therefore, the existing methods are not ideal to protect devices against unauthorized access. Many studies have shown that such devices can be accessed using fake fingerprints made from play dough, gelatin, silicone, glue, etc. This approach does not provide for anti-spoofing analysis, i.e. a fake detection analysis.
Even if biometric devices use physiologic information to identify the user, conventional methods using capacitive sensors may not detect whether the user applies a “live” finger, i.e., detection of living tissue. Therefore, a user authentication system with a preliminary anti-spoofing analysis is desirable. Thus, a further layer of authentication can be performed by determining whether the user's biometric data is acquired from a real “live” finger.
Certain embodiments as disclosed herein enhance the security of access to devices with biometric authentication when a user having access rights to the device uses an apparatus for registration and appropriate check. According to some embodiments provided by the present disclosure, the anti-spoofing analysis is the result of detecting anisotropy of the tissue in the fingertip.
A conventional biometric authentication system using a fingerprint is disclosed, for example, in patent document U.S. Pat. No. 6,181,808 B1 (“Living Body Discriminating Apparatus”, NEC CORPORATION). The disclosure teaches a discriminating apparatus, which is capable to discriminate whether a live finger or a fake was used to input information. The discrimination comprises measuring the potential difference between two muscle points of the finger using at least two electrodes and a grounding electrode, wherein at least two electrodes are disposed in the region of the finger bone. Using a plurality of electrodes and the grounding electrode, a table of potentials can be produced for use in detection of a fake. By analyzing frequency data and data of potentials received from the electrodes, the apparatus determines whether a live finger was used to enter the data. However, such a system does not provide for detection of anisotropy, so a fake made of a material having the same or similar conductivity properties as living tissue can be used. Such a fake finger may be produced for example, using methods of copying dielectric properties of tissues by mixing water, salt, agar, and polyethylene powder.
Moreover, the aforementioned systems contemplate stringent requirements on the finger position, such as requiring the first joint of the finger to be positioned on the sensor where the grounding electrode is disposed. Further, the measurement period for the aforementioned systems can be quite long (about 0.5 sec) due to the necessity to receive a signal, on the basis of which a data set is determined, in some time interval.
Patent document U.S. Pat. No. 5,990,804 A (“Animate Body Detector” SONY CORPORATION) discloses a detector used to determine whether an object to be checked (fingertip) is an animate body. The determination is made by measuring capacitance, rate of capacitance variation over a predetermined time, moisture and pressure by electrodes and related sensors. This patent document further describes contactless procedure of measuring the listed characteristics. However, the disclosure does not provide for detection of tissue anisotropy either, so a fake can be made of a material having the same or similar conductivity properties as living tissue. At the same time, due to the fact that measurements of variations in living tissue characteristics cannot be made out in parallel, the determination is quite long due to the necessity to acquire various data over time.
Certain embodiments according to the present disclosure provide systems and methods for recognition of living tissue offering higher accuracy of detecting a fake by performing a measurement of anisotropy.
Certain embodiments according to the present disclosure provide a method for recognition of living tissue offering reduced times for identifying whether a sample comprises living or non-living tissue. According to certain embodiments, the identification may take less than 0.3 sec.
The identification of living or fake tissue is attained by embodiments of a method and apparatus such as described in the independent claims. Additional embodiments of the present disclosure are described in the dependent claims.